fix(mdviewer): re-render from CM content on edit→reader switch for cursor sync

When switching from edit to reader mode, MarkdownSync now sends the
current CM document text back to the iframe. The iframe re-parses it
to produce fresh data-source-line attributes so cursor sync works on
newly edited elements.

Author: abose

src-mdviewer/src/bridge.js

@@ -290,6 +290,8 @@ export function initBridge() {
     on("bridge:contentChanged", ({ markdown }) => {
         if (_suppressContentChange) return;
         _syncId++;
+        // Keep state.currentContent in sync so edit→reader re-render has latest content
+        setState({ currentContent: markdown });
         // Update the cache entry's mdSrc so it stays in sync
         const activePath = docCache.getActiveFilePath();
         if (activePath) {
@@ -594,8 +596,16 @@ function handleSetTheme(data) {
 }
 
 function handleSetEditMode(data) {
-    const { editMode } = data;
+    const { editMode, markdown } = data;
     setState({ editMode });
+
+    // When switching to reader, re-render from CM's current markdown
+    // so all elements get fresh data-source-line attributes for cursor sync.
+    if (!editMode && markdown) {
+        const parseResult = parseMarkdownToHTML(markdown);
+        setState({ currentContent: markdown, parseResult });
+        emit("file:rendered", parseResult);
+    }
 }
 
 

src/extensionsIntegrated/Phoenix-live-preview/MarkdownSync.js

@@ -107,7 +107,11 @@ define(function (require, exports, module) {
                 _handleRedo();
                 break;
             case "mdviewrEditModeChanged":
-                // Could be used to sync edit mode UI state in Phoenix if needed
+                // When switching to reader, send CM content back so the iframe
+                // can re-render with accurate data-source-line for cursor sync.
+                if (!data.editMode && _doc) {
+                    setEditMode(false);
+                }
                 break;
             case "mdviewrRequestEditMode":
                 if (_onEditModeRequest) {
@@ -707,7 +711,13 @@ define(function (require, exports, module) {
         }
         const iframeWindow = _getIframeWindow();
         if (iframeWindow) {
-            iframeWindow.postMessage({ type: "MDVIEWR_SET_EDIT_MODE", editMode: editMode }, "*");
+            const msg = { type: "MDVIEWR_SET_EDIT_MODE", editMode: editMode };
+            // When switching to reader, include current CM content so the iframe
+            // can re-render with accurate data-source-line attributes for cursor sync.
+            if (!editMode && _doc) {
+                msg.markdown = _doc.getText();
+            }
+            iframeWindow.postMessage(msg, "*");
         }
     }